A device for selectively determining the quantity of mist is known from DE 10 2006 023 714 B4. The prior-art measuring sensor is based on the so-called impactor principle, in which an air jet loaded with oil mist or aerosols is suddenly deflected in order to collect the deposited oil particles or aerosol particles on a deflector. The gas sample to be analyzed now flows through a plurality of micronozzles, which are arranged in a circle and whose diameter is selected to be such that a predetermined test gas flow will become established. The micronozzles are arranged in this case at the end of a gas inlet duct, and the deflector, at which the oil or aerosol particles are deposited, is located opposite the micronozzles. The quantity of oil or aerosol particles collected during a certain measurement time is an indicator of the oil or aerosol content in the gas sample.
The gas sample to be analyzed is usually taken from a pressure source, e.g., a central compressed air supply system in order to make it possible to carry out the gas analysis. The gas inlet duct of the measuring sensor is connected for this to the gas source via a connecting branch, and the micronozzles act as nozzles to which supercritical gas flow is admitted and they limit the flow quantity.
The drawback of the prior-art measuring sensor is that the gas analysis can be only carried out on a pressurized gas reservoir, whereas detection of oil mist or aerosols in the ambient air is not possible.